Observations of ELF Propagation at High Latitudes During the Sporadic-E Conditions of November 1986
Abstract
Researchers in extremely low frequency (ELF) radio propagation have speculated on the effects of disturbed ionospheric conditions. Over the years, it has been observed that, although the propagation of ELF signals is remarkable for its relative stability, these signals are nevertheless influenced by many of the same types of disturbances that afflict higher frequency bands. Some of the early measurements revealed not only ELF's stable, predictive features (e.g., the smooth transitions through daytime and nighttime periods), but also its unexplainable, sudden decreases in nighttime signal strength. One of the most dramatic natural events for the radio propagationist to study is the solar proton event (SPE). During polar-cap absorption (PCA) events, an earthly response to an SPE, energetic protons from the sun penetrate the polar ionosphere. In the process, interactions with a variety of atmospheric constituents result in an increase in the ionization density to altitudes of 30 km or less.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 11, 1994
- Accession Number
- ADA284973
Entities
People
- D. J. Saleem
- J. R. Katan
Organizations
- Naval Undersea Warfare Center